芯片级CPT原子钟的研制

Manufacture of chip scale CPT atomic clock

报道了一款尺寸大小、引脚定义和主要功能与美国SA.45s芯片级原子钟兼容的低功耗小体积CPT(coherent population trapping)原子钟。研制工作以降低工艺难度,易于工程实现为原则,回避了技术难度较大的MEMS(micro electro mechanical systems)技术和高真空绝热等技术工艺。其物理部分以边长3.5 mm的传统立方形玻璃气室为核心,填充^(87)Rb原子和缓冲气体;电路部分以低功耗STM32单片机为核心。对整机零部件进行体积和功耗的优化并通过软件算法对频率温度特性进行学习和智能补偿,最终产品外形尺寸为4.0 cm×3.5 cm×1.2 cm,重量30 g,稳态功耗0.53 W。样品经中国计量院校准,启动时间2 min 15 s,跟踪外秒24 h稳定性50 ns峰峰值,跟踪外秒1天后断开外秒24 h最大偏差1.4μs,短期频率稳定度7.1×10^(12)/1 s,相位噪声-101 dBc/Hz@10 Hz。主要技术指标达到或接近典型的芯片级原子钟的水平。

A low power consumption and small volume CPT atomic clock with size, pin definition and main functions compatible with American Chip-Scale-Atomic-Clock SA.45 s is reported.The development work is based on the principle of simplifying the process technology, without using the MEMS(micro electro mechanical systems) gas chamber technology and high vacuum heat insulation technology.The physical part takes the traditional cube glass gas chamber with a side length of 3.5 mm as the core, filled with ^(87)Rb atoms and buffer gas;The circuit part takes the low-power-consumption STM32 MCU as the core.The hardware volume and power consumption were optimized, and the characteristic of frequency vs.temperature was intelligently compensated through software.The overall dimension of the final product is 4.0 cm×3.5 cm×1.2 cm, the weight is 30 g, and the steady-state power consumption is 0.53 W.A sample product was calibrated in NIM(National Institute of Metrology),and the certificate shows the start-up time is 2 min 15 s, the tracking stability is 50 ns peak to peak value, the 24 h’s holdover error is 1.4 μs, the short-term stability is 7.1×10^(12)/1 s, the phase noise is-101 dBc/Hz @ 10 Hz.The main technical specifications are close to those of a typical chip scale atomic clock.